A think a DCT M3 (non-E93) with a tune, headers and full exhaust would be fairly equal a C63 with PP. The C63 could also get a tune, headers and exhaust I suppose and be faster then again.

To me, though, this stuff isn't all that important. I don't measure my manhood based on stop light races I would still pick the M3 as a track oriented car and a C63 as a DD street car (although the M3 is great for that too). Both are very fast (more than needed for public roads) and even if the C63 with PP is a little faster it doesn't really matter that much unless someone just "needs" to win the next stop light race to fuel their ego.

A C63PP with tune only will rape any FBO M3. More so from a standstill (although wheelspin is massive in a C63PP as you already know). I've driven both (obviously the C63PP less than you) and agree with you with picking the M3 as a more track oriented car. However, MB is catching up quickly...